The present invention relates to an image data processing method for processing data to produce image data to be supplied to a recording device for effecting image recording in accordance with image data using a recording head having a plurality of recording elements, an image data transfer method for transferring the image data, and a recording material for executing the methods.
Image forming apparatuses for recording on a recording material such as paper, an OHP sheet use various recording type heads. The types of the recording heads include a wire dot type, a thermosensitive type, a thermal transfer type, an ink jet type or the like. Among them, the ink jet type is widely used in the fields of printer, facsimile machine, copying machine or the like because of the advantages in the low noise, the low running cost, the small size, the easiness in use for color printing.
The recording head of the ink jet recording apparatus includes a plurality of ink ejection outlets (nozzles) arranged in a direction parallel to the feeding direction of the recording material, and ink droplets are ejected through the ejection outlets.
In an ink jet recording apparatus using the recording head having a plurality of nozzles, the ejection performances of the nozzles become different from each other due to elapse of time or due to manufacturing error with the result of unevenness of density which may be stripes, in the printed image.
In order to solve the problem, Japanese Laid-open Patent Application No. HEI 5-220977 has proposed that density correction data are prepared for each nozzle, on the basis of which a raster signal for the original image is corrected in the density for each nozzle, so that density non-uniformity and stripes of the image are avoided (head shading method).
The head shading disclosed in Japanese Laid-open Patent Application No. HEI 5-220977 is employed in a copying machine image an original image read from an original document by a reading apparatus is printed on a recording material by an ink jet recording apparatus, but the method can be incorporated in a printer system. Generally in a printer system, a host computer obtains multi-level image data from various image file or application, and a printer driver converts the data into binary image data, which is supplied to a printer, which in turn prints the corresponding image in accordance with the image data.
Therefore, when the host computer, more particularly, the printer driver is provided beforehand with the property of the recording head of the printer, that is, the density correction data, the printer driver can correct the multi-level image data in the image density in accordance with the properties of the recording head before conversion to binary image data.
On the other hand, the printer system carries out various operations for high speed printing and for high image quality printing. For example, a high image quality printing is accomplished by a so-called multi-path printing. In this system, the distance or amount of paper feeding corresponds to 1/n multiplied by the number of used nozzles, and the main-scanning printing is effected n times with data which have been complementarily thinned to 1/n so that one raster line is printed using a plurality of (n) nozzles. The multi-path printing is effective to suppress the error of the paper feeding, the differences in the ejection properties of the nozzles (quantities of the ejected liquid, the directions thereof), the unevenness in the darkness due to the differences in the ink absorbing speed attributable to the paper material property, so that image quality is improved.
As for an example of high speed recording, a so-called null skip is known. The printer having received the image data simply feeds the sheet without effecting the main-scanning operation of the recording head for the raster line having no print image data, thus speeding the printing operation.
However, the head shading method is not usable, as it is, with the printer using the multi-path printing or null skip system, since in the head shading method, the density correction is carried out on the basis of simple correspondence between the nozzles and the image data using the density correction data for the nozzles.
In the multi-path printing, the 1raster line is covered by a plurality of nozzles. In the head shading method a density correction table is prepared for each nozzle in accordance with each of the properties of the nozzle. If this correction system is used as it is, the density correction for each raster line is effected using a density correction table for a certain one nozzle despite the facts that 1raster line is printed by a plurality of nozzles with the result that density correction table does not match the actually used nozzle, and therefore, the object of improving the image quality is not accomplished.
On the other hand, when the printer effects the null skip on the basis of the binary image data after the density correction, the image data which have been subjected to the density correction are printed by a nozzle different from the nozzle for which the correction has been made, that is, the correction does not match the actual printing nozzle. Moreover, the original image is not faithfully reproduced. More particularly, a raster line which is not a null line before the density correction, may become a null line by the binarization process or by the density correction. If the null skip is carried out for such a raster line, the above-described inconvenience arises.
The problem may be solved by supplying the multi-level image data from the printer driver to the printer and by the printer effecting the density correction in accordance with the properties of the recording head. However, such a method results in that multi-level image data are supplied to the printer of the printer driver so that time required for transmitting the image data becomes longer, and that density correction and the binarization process are effected in the printer. Therefore, it is not practical.
Accordingly, it is a principal object of the present invention to provide an image data processing method and an image data transfer method capable of permitting high image quality recording despite various operations carried out by the recording device, and a recording material storing a control program therefor.
According to an aspect of the present invention, there is provided an image data transfer method for transferring image data to a recording device for effecting an image recording in accordance with the image data using a recording head having a plurality of recording elements, said method comprising a step of simulating a recording operation of the recording device in accordance with a predetermined condition; a step of providing correspondence between raster lines of the image data and recording elements to be used for recording the raster lines on the basis of a result of said simulating step; a step of effecting an image processing the image data for each raster lines having been made to correspond to the recording elements by said correspondence providing step; a step of transferring the image data having been subjected to the image processing to the recording device.
According to this aspect of the present invention, the recording operation of the recording device corresponding to the multi-path printing, the null raster skip, the color containing image printing, black-color image printing, the break image, the operation against the change of the ambient condition or the like are simulated, and then on the basis of the result of simulation, the raster lines of the image data are made correspond to the recording elements, and the image data for the raster lines corresponding to the recording elements are subjected to be image processing, and the image data thus processed are transmitted to the recording device.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following invention taken in conjunction with the accompanying drawings.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.